1. Field of the Invention
The invention relates to a timing circuit as well as apparatus that utilizes this timing circuit. The apparatus is particularly suited for use with a telephone network interface, for substantially preventing a third party who gains access to the interface from placing an unauthorized telephone call through a network connection obtained through this jack located in a customer portion of the interface.
2. Description of the Prior Art
In the current deregulated telephone environment, a local telephone company ("telco") provides a subscriber loop (telephone line), and both local telephone service and access through its switching facilities for its local subscribers to long distance vendors, but is generally not responsible for the wiring ("inside wiring") and telephone equipment existing inside a subscriber's premise. As such, a physical point of demarcation typically exists on a subscriber loop where the responsibility over that loop shifts from a local telco to a particular subscriber. Having defined such a point for each loop, it has become quite advantageous over the past few years to connect test equipment through a telephone network interface to each subscriber loop at its point of demarcation. Doing so allows the subscriber, interconnect company or local telco to test the loop and thereby determine not only whether a fault exists in the loop but also, importantly, whether that fault lies within the local telco portion of the loop or within the subscriber's portion, i.e. inside wiring and customer premise equipment connected thereto. This test equipment may illustratively contain circuitry that tests the amplitude and frequency of dial tone provided by the central office and appearing on the loop at least up to its point of demarcation. One example of such subscriber loop test equipment is described in detail in U.S. Pat. No. 4,679,224 (issued July 7, 1987 to D. Lynch et al and owned by the present assignee).
For the convenience of the local telco, the point of demarcation, at which the subscriber loop telephone network interface is located, should be situated at a location which is readily accessible to telco maintenance personnel. As such, for a residential premise, the telephone network interface is typically situated outside of the subscriber's premise. This network interface generally has a first or "telco" portion which contains the actual subscriber loop wiring and a lightning arrester and appropriate wiring connections leading to a modular, typically type RJ 11, telephone jack. A second or "customer" portion of the interface contains a wiring or entrance bridge connected through a short length of telephone cable to typically a modular RJ 11 plug that mates with the jack. Customer wiring terminates at four screw terminals located on the wiring bridge. Different line entrances exist on the enclosure. These entrances permit a telco to separately route its end of a subscriber loop to appropriate terminals residing within the telco portion of the interface; while a customer can route an end of its inside wiring to the screw terminals situated on the entrance bridge located within the customer portion of the interface. Normally, a subscriber can gain access through a door only to the second portion of the enclosure, while telephone maintenance personnel can gain access to the entire enclosure through a different door. The enclosure is provided with a lock loop through which the customer can attach a lock in order to secure the customer portion of the enclosure.
Through use of such a telephone network interface and specifically through the modular jack contained therein, a telephone maintenance person can easily disconnect the telephone plug leading to the wiring bridge and instead connect a telephone to the telco end of the subscriber loop for any additional loop tests. Although the customer portion of the enclosure is expected to be locked in order to shield the modular jack from anyone who is not associated with either the subscriber or the telco, any lock can, with sufficient effort, be compromised by third parties. Moreover, the customer may be remiss in its responsibility to install a lock on its portion of the enclosure in order to thwart third party access. In any event, once a third party gains access to the customer portion of the interface and specifically to the jack situated therein, that party could merely unplug the subscriber wiring from the modular jack and, in its place, plug a telephone into the jack in order to obtain a network connection. Through this connection, the third party would obtain dial tone and be able to place unauthorized telephone calls through the subscriber's loop.
Presently, the use of telephone network interfaces is relatively new in the telephone industry. As such, the vast majority of subscriber lines, particularly those that have been in place for quite a number of years, generally five or more, do not yet possess such interfaces. Accordingly, due to the relatively small number of these interfaces currently in use as compared to the total number of telephone subscriber loops that are currently in service, theft of telephone services through these network interfaces has not yet reached significant or, for that matter even noticeable, proportions. Nevertheless, as the use of these interface continues to proliferate, more and more loops will unfortunately become susceptible to unauthorized third party access through these interfaces. Accordingly, the number of fraudulent calls made by unauthorized third parties through physical connections established through these interfaces is likely to significantly increase, unless sufficient measures are taken to curb their occurrence. Ultimately, as with other types of telephone fraud, the costs of such calls will likely be transferred by the telcos, through increased rates, to all of their local telephone subscribers.
Given the current limited use of telephone network interfaces and the present lack of appreciable or even noticeable telephone service theft therethrough, the art has not yet recognized, much less addressed, the problem of effectively preventing such theft--though the need to do so increases each day as additional network interfaces are installed on new or existing subscriber loops.
Therefore, an increasing need currently exists in the art for apparatus, and a method for use therein, for use in conjunction with a telephone network interface for substantially preventing an unauthorized third party who gains access to a customer portion of the interface from placing unauthorized telephone calls over a subscriber loop through the interface, and specifically through a modular jack associated therewith. Advantageously, by meeting this need now, a future source of telephone fraud can be substantially eliminated before it reaches noticeable proportions and adversely affects local telephone rates.